wxTimerEvent object is passed to the event handler of timer events.
For example:
class MyFrame : public wxFrame
{
public:
    ...
    void OnTimer(wxTimerEvent& event);
private:
    wxTimer m_timer;
};
BEGIN_EVENT_TABLE(MyFrame, wxFrame)
    EVT_TIMER(TIMER_ID, MyFrame::OnTimer)
END_EVENT_TABLE()
MyFrame::MyFrame()
       : m_timer(this, TIMER_ID)
{
    m_timer.Start(1000);    // 1 second interval
}
void MyFrame::OnTimer(wxTimerEvent& event)
{
    // do whatever you want to do every second here
}
Derived fromInclude files
<wx/timer.h>
See also
Members
int GetInterval() const
Returns the interval of the timer which generated this event.